Stratigraphy and integrated facies analysis of the Saalian and Eemian sediments in the Amsterdam-Terminal borehole, the Netherlands

Abstract

The Amsterdam glacial basin was a major sedimentary sink from late Saalian until late Eemian (Picea zone, E6) times. The basin’s exemplary record makes it a potential reference area for the last interglacial stage. The cored Amsterdam-Terminal borehole was drilled in 1997 to provide a record throughout the Eemian interglacial. Integrated facies analysis has resulted in a detailed reconstruction of the sedimentary history.After the Saalian ice mass had disappeared from the area, a large, deep lake had come into being, fed by the Rhine river. At the end of the glacial, the lake became smaller because it was cut off from the river-water supply, and eventually only a number of shallow pools remained in the Amsterdam basin. During the early Eemian (Betula zone, El), a seepage lake existed at the site. The lake deepened under the influence of a steadily rising sea level and finally evolved into a silled lagoon (late Quercus zone, E3). Initially, the lagoon water had fairly stable stratification, but as the sea level continued to rise the sill lost its significance, the lagoon becoming well mixed by the middle of the Corylus/Taxus zone (E4b). The phase of free exchange with the open sea ended in the early Carpinus zone (E5), when barriers developed in the sill area causing the lagoon to become stratified again. During the Late Eemian (late E5), a more dynamic system developed. The sandy barriers that had obstructed exchange with the open sea were no longer effective, and a tidally-influenced coastal lagoon formed.The Eemian sedimentary history shown in the Amsterdam-Terminal borehole is intimately connected with the sea-level history. Because the site includes both a high-resolution pollen signal and a record of sea-level change, it has potential for correlation on various scales. Palaeomagnetic results show that the sediments predate the Blake Event, which confirms that this reversal excursion is relatively young. The U/Th age of the uppermost part of the Eemian sequence is 118.2±6.3 ka.

Probabilistic assessment of sea level during the last interglacial stage

“…Relative age constraints are provided by characteristic Eemian pollen zones, many of which have durations established to fairly high precision based upon the counting of varves in an annually-layered lacustrine diatomite in northwestern Germany (Zagwijn, 1996). We place peak sea level in the middle third of zone E5 based upon the position of the maximum flooding interval within the more recent Amsterdam-Terminal borehole (van Leeuwen et al, 2000). We estimate absolute ages from these relative ages by aligning the sea level curve against the Lisiecki and Raymo (2005) global oxygen isotope stack.…”

Radiocarbon Dating of Late Pleistocene Marine Shells from the Southern North Sea

“…• Furthermore, in core B25E0913 (Appendix 1), we collected a nonfinite, ~45 14 C kyr BP age from the same V. senescens shell from which a 118 ± 6 ka age was presented by Van Leeuwen et al (2000).…”

The Blake Event recorded near the Eemian type locality – A diachronic onset of the Eemian in Europe

“…1). This morphology surrounds and constrains the last-interglacial marine embayment that contains the deposits that host the Eemian type sections at Amsterdam and Amersfoort (Harting, 1874;Van Leeuwen et al, 2000;Zagwijn, 1961). In the embayment, the sedimentary contact of the Eemian transgression with its typical marine mollusc and palynological indicators, is well recognizable.…”